chum chum /ˈtʃʌm/

noun

1. [Informal] A large Pacific salmon with small spots on its back; an important food fish  ( chum [Informal] , chum salmon , Oncorhynchus keta )
   a large Pacific salmon with small spots on its back; an important food fish
   
2. [Informal] Bait consisting of chopped fish and fish oils that are dumped overboard to attract fish  ( chum [Informal] )
   bait consisting of chopped fish and fish oils that are dumped overboard to attract fish
   
3. A close friend who accompanies his buddies in their activities  ( brother , chum , pal , buddy , crony , sidekick )
   a close friend who accompanies his buddies in their activities
     Jake and Mark had been best buddies since kindergarten.
   Jake and Mark had been best buddies since kindergarten.